High-Resolution Noncontact Atomic Force Microscopy Provides a Glimpse of the Electron Orbital Signatures of Single Atoms

Scientists have always been fascinated with understanding the interaction of atoms and the formation of chemical bonds. Such information provides the key to identifying reaction pathways. However, they are facing the challenge of directly measuring the electronic structure of a single atom or a chemical bond. Various strategies have been employed to explore molecular orbital spreading under certain conditions.

With supercomputer simulations and atomic-resolution imaging tools, scientists can now glimpse the electron orbital signatures. In quantum mechanics, understanding electron orbitals allows scientists to describe the region within the atom where the electrons are most likely to be found.

Taking a Glimpse of Electron Orbital Signatures

Researchers from UT Austin, Princeton University, and ExxonMobil collaborated to investigate the signatures of electron orbitals in iron and cobalt found in metal-phthalocyanines. These signatures manifest in the forces calculated by atomic force microscopy, revealing the orbitals for interpretation.

In experiments, a high-resolution noncontact atomic force microscopy (HR-AFM) investigated the direct identification of iron and cobalt. The researchers also use electronic structure calculations based on density functional theory (DFT) since it is a practical method for predicting the behavior of materials. At the end of their experiment, the researchers discovered that the cobalt atom is brighter and has distinct lobes on the horizontal planes. In contrast, an iron atom displays a square morphology.

Iron and cobalt are adjacent in the periodic table, implying similarities in their properties. However, reproducible experimental differences were observed from the force spectra and measured images of these elements, as confirmed by study co-author James R. Chelikowsky from UT Austin. His team was surprised to observe these subtle differences, considering they are tiny forces.

Chelikowsky also said that their technique of using atomic force microscopes to observe the signatures of electron orbitals helps explore the behavior of individual atoms and molecules. It can also contribute to designing and engineering new materials with specific characteristics. Such contribution has a great advantage in the fields of nanotechnology, materials science, and catalysis.

This study also includes an inert molecular probe tip used in approaching another molecule and measuring their interactions, allowing the team to investigate specific surface chemical reactions.

What is Atomic Force Microscopy?

Atomic force microscopy (AFM) is a technique used to capture surface images, such as composites and polymers. It is also an effective tool for measuring and localizing various forces, including magnetic forces, adhesion strength, and mechanical characteristics. As an observation strategy, it takes advantage of the atomic forces that hold together the probe and the sample surface. Aside from atom imaging, AFM can also be used in manipulating atoms and structures on various surfaces.

In the field of nanotechnology, AFM is beneficial in nanoscale processing for structured coatings. AFM is a flexible technique that allows scientists to gather high-resolution nanoscale images and understand their local sites in air or liquid surroundings.